How to get the library paths of a meson dependency? - libraries

Question

Use case: I have a dependency that falls back to a subproject:
./
./subprojects/
./subprojects/mylib.wrap
src/meson.build contains:
mylib_dep = dependency('mylib') # Searches for mylib with pkg-config then fall backs to mylib.wrap.
myexec_exe = executable ('myexec', 'myexec.c', dependencies : mylib_dep)
Dependency mylib_dep provides libraries, which, if not installed on the system, make the main executable of my project unusable:
$ meson build && cd build && meson compile src/my_exec
...snip'd...
$ src/my_exec
src/my_exec: error while loading shared libraries: libmylib.so: cannot open shared object file: No such file or directory
My testing script build/tests/mytests.sh is configure_filed from tests/mytests.sh.in to indicate the location of myexec, and I'd like to pass to it the library paths, so that it can adjust LD_LIBRARY_PATH and run the executable. For instance, in tests/meson.build:
conf_data = configuration_data ()
conf_data.set_quoted ('MYEXEC_PATH', myexec_exe.full_path ())
conf_data.set_quoted ('MYLIB_PATH', mylib_dep.??????)
mytest_exe = configure_file (input : 'mytests.sh.in', output : 'mytests.sh', configuration : conf_data)
and in tests/mytests.sh.in:
MYEXEC_PATH=#MYEXEC_PATH#
MYLIB_PATH=#MYLIB_PATH#
export LD_LIBRARY_PATH=$(dirname "$MYLIB_PATH"):$LD_LIBRARY_PATH
$MYEXEC_PATH
Question: What should go at the ?????? above? In other words, given a dependency object, how can I extract the libraries within it, and get their full paths?

Answer 1

Usually in meson you wouldn't configure_file this, you'd pass the library/executable(s) to the script as arguments in the test command:
test(
'mytest',
find_program('mytest.sh')
args : [executable_target, library_target, ...],
)

Answer 2

It can be frustrating trying to get this sort of info out of Meson. Fortunately, if Meson used CMake to find the dependency, you may be able to get the library path from the underlying CMake variables, which are available in the Meson dependency object. Eg, something along the following lines worked for me:
mylib_dep = dependency('mylib')
if mylib_dep.found()
mylib_path = mylib_dep.get_variable(default_value : '', cmake : 'PACKAGE_LIBRARIES')
message('Library path is:', mylib_path)
endif